This project is designed to further elucidate the role of near-UV light in ocular tissue damage. One objective is to look for cytotoxic and biochemical alterations in the lenses and retinas of mice and other animals exposed chronically to subsolar levels of near-UV light in several wavelength ranges. We seek abnormal development of lens epithelial cells into fiber cells, increased aggregation of lens proteins, and the degeneration of retinal photoreceptors. The feeding of antioxidants and reducing agents will be used to slow or prevent these damages. Another objective is to study human lenses of different age and with various types of cataracts that can be obtained from geographical areas with differing levels of sunlight so as to assess the role of sunlight as a factor in human lens pathology. We look for a relationship between the transmission properties of the lens and the form and chemical properties of its proteins (molecular size, pigmentation, fluorescence). We also will ascertain some of the basic changes of near-UV light on ocular tissue cells in vitro and specifically on certain enzymes essential for their function. We propose studies of the influences of near-UV light with and without sensitizers on cell growth, mitosis, and macromolecule synthesis, and without sensitizers on ocular tissue and purified enzymes (activity and chemistry). Here too chemical antagonists of the damaging effects will be studied. The overall objective, then, is to learn how near-UV light and some of its photoproducts can damage the lenses and retinas of animal and human eyes, and to test the efficiency of antioxidants and free radical scavengers in preventing this damage.